"Union members are canvassing across Kansas City ahead of a battleground vote over right-to-work policy in Missouri.

We Are Missouri campaigners are asking residents to repeal the state's right-to-work law in the primary on Tuesday, the Kansas City Star reported. The union-backed political action committee is fighting against a coalition of three PACs, including Missourians for Freedom to Work.

The right-to-work issue will appear on the Missouri ballot Tuesday under Proposition A. Voters will decide whether to appeal or uphold the policy passed by the state General Assembly and signed by then-Gov. Eric Greitens last year. A coalition of labor groups petitioned to put the law up for a vote.

Supporters of the law argue that it gives workers the freedom to choose whether to support the union at their workplace. Workers are able to opt-out of full union membership and dues, but they can also pay fees to cover unions' collective bargaining and representation services.

Union-backed opponents have said the policy lowers wages and weakens unions by allowing free-riders who aren't paying for its services."